Signaling system for single-track railways



N. D. PRESTON.

SIGNALING SYSTEM FOR SINGLE TRACK RAILWAYS.

APPLICATION FILED JULYB. 191s. RENEWED 05c. 11,1919.

1,386,073, Patented Aug. 2, 1921.

INVENTOR BY a 2; 5.4919 1,

ATTORNEY UNITED STATES PATENT OFFICE.

NEIL D. PRESTON, OF ROCHESTER, NEW YORK, ASSIGNOR 'IO GENERAL RAILW'AY SIGNAL COMPANY, OF GATES, NEN YORK, A CORPORATION OF NEIV YORK.

SIGNALING SYSTEM FOR SINGLE-TRACK RAILWAYS.

Application filed July 8, 1918, Serial No. 108,182.

T 0 all witomit may concern:

Be it known that I, NEIL D. PnnsroN, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, have invented a new and useful Signaling System for Single-Track Railways, of which the following is a. specification.

This invention relates to signaling systems for railroads, and more particularly to signaling systems for single track railroads of the type which are termed absolute permissive block signaling systems.

In one type of signaling systems for single track railroads, to which this invention particularly relates, certain signals are governed in one way by trains moving in one direction and in another way by trains moving in the opposite direction; and in order to change the character of the control of these signals depending upon the direction of movement of the trains, there is used a relay, which, because of the way it is controlled, is commonly called a stick relay. In one form of signaling system of this type there is a stick relay, associated with each of certain signals, which is energized by a train traveling in one direction and is held energized while this train occupies a predetermined portion of the track in advance of the corresponding signal; and when energized this stick relay modifies the control of the signal in the rear of the signal corresponding to the stick relay. T his invention relates more specifically to this type of single track signaling systems, although it is appreciated that the features of the invention may be advantageously a plied to other types or forms of signaling systems.

One object of this invention is to devise a signaling system for single track railroads of the general character above described and including stick relays such that each stick relay is energized bytrains traveling in one direction only.

A. further object ofthe invention is to devise a signaling system of the character above described and including stick relays such that each stick relay is not energized until it is necessary to use the controlling action which the stick relay is capable of performing.

A still further object of the invention is to devise a signaling system of the character Specification of Letters Patent.

Patented A11 2, 1921.

as the description of the invention progresses, and the novel features-of the invention will be particularly pointed out in the appended claims.

Generally stated, the invention consists in the parts, and in the arrangements and combinations of parts, together with the electrical controlling circuits therefor which are more fully set forth hereinafter.

In describing the invention in detail reference is had to the accompanying drawing in which is illustrated a preferred physical embodiment of the invention, in which like reference characters designate like parts in the several views, and in which:

Figure 1 is a schematic view showing a stretch of single track between two passing siding-s, and an arrangement of signals suitable for governing traffic over this stretch;

and

Fig. 2 is a diagrammatic view showing an arrangement of controlling devices and electrical circuits therefor constituting a part of the signaling system schematically shown in Fig. 1.

Referring to Fig. 1, there is illustrated a stretch of single track, indicated by a single heavy line, and a passing siding S and S at each end of this stretch of. track. The stretch of single track is divided by insulating oints 3 in the usual manner into a num ber of track sections designated A, B, C, D, E and F. Each one of these track sections is provided with a track battery and a track relay as in the usual construction, and these track relays govern other relays and controlling circuits for governing tilt) operation of the signals governing tratfic over the stretch of track, a portion of these controlling circuits, together 'ith the other relays being shown in detail in Fig. 2 and more fully described hereinafter. In Fig. 1 there are illustrated signals 5, 6, 7 and 8 for governing traffic from right to left, in the direction indicated by the arrow Y, and sig nals 9, 1O, 11 and 12 for governing traffic from left to right, in the direction indicated by the arrow X. The signals 8 and 9 located at the right and left hand end of the stretch of single track, respectively, are of the type commonly known as an absolute signal, whereas the other signals are'of the type commonly known as permissive signals. The characteristics of these different kinds of signals are well known in the art, and for the purpose of understanding this invention it is deemed unnecessary to further discuss the significance attached to these different types of signals, or to describe in detail wherein these signals are distinguishable, since this invention is in no wise dependent upon any particular kind'of signals and may be advantageously used with light signals, as well as with the well known semaphore signal. In Fig. 1, however, the well known semaphore type of signal is shown; and in this case the absolute signals 8 and 9 are made distinguishable from other permissive signals by reason of the fact that these absolute signals have square ended blades, while the permissive signals have pointed blades.

The general scheme of operation of the signaling system sch ematically shown in Fig. 1 may be briefly described as follows: The movement of a train in either direction upon the stretch of single track causes all of the signals governing traffic in the opposite direction to assume their biased stop position; that is, if a train enters the track section A while traveling in the direction indicated by the arrow X, the signals 6, 7 and 8 governing traffic in the opposite direction assume their stop position. As the train progresses along the stretch of single track these opposing signals governing traiiic in an opposite direction are held in their stop position until the trainpasses them; that is, with a train traveling in the direction indicated b the arrow X, the signal 6 will be held in the stop position until the train has entirely passed this signal, the signals 7 and S being also held in the stop position in the meantime, the signal 7 will be held in the stop position until the train entirely passes this signal, and likewise the signal 8 will be held in its stop. position until the train has entirely left the track section F. In this way, when a train enters the stretch of single track from either end, the entrance of any other train into said stretch at the opposite end is prevented. Furthermore, when a train enters the stretch of single track traveling in either direction, the signals governing traffic in the direction in which the train is traveling are successively caused to assume, first, a horizontal or stop position, second, a diagonal or caution position and a vertical or clear position; that is, with a train traveling in the direction of the arrow X, the signal 9 is in the stop position while this train occupies the track sections A and B, is in the diagonal or caution position while thetrain occupies the track sec 'tions C and D, the signal 10 at this time being in the stop position; and when the train proceeds into the track sections E and F the signal 11 assumes its horizontal or stop position, the signal 10 its diagonal or caution position, and the signal 9 its vertical or clear position. In this way, while one train is passing through the stretch of single track, another train traveling in the same direction as the first train, may enter said stretch of track and be properly governed by signals. In this connection it is stated that the control of the signals to the diagonal or caution position is not shown in detail in the diagrammatic illustration in Fig. 2, since various arrangements for causing a signal to assume its diagonal or caution position when the next signal in advance is in the horizontal or stop position are well known in the art, and if illustrated in Fig. 2, will only serve to unnecessarily complicate the drawing.

In Fig. 2 of the drawing there are shown track sections A, B, C and D corresponding to the track sections A, B, C and D in Fig. 1, and controlling circuits suitable for go verning the signals 9 and 10, also corresponding to the signals 9 and 10 in Fig. 1. In Fig. 2, the numerals 1 and 2 designate the track rails of the stretch of single track, the separate rail sections thereof being suitably bonded together in the well known manner, and the numeral 3 designates insulating joints interposed in the track rails 1 and 2 and serving to divide the track into the electrically isolated track sections A, B, C and D. At one end of each track section a track battery t is connected across the track rails l and 2; and at the other end of each track section a track relay is connected across said track rails, the track relays for. the track sections A, B, C and D being designated 13, 14, 15 and 16, respectively. Associated with the signal 9 is a relay 17, hereinafter termed a line relay, and associated with the signal 10 is a line relay 18. Associated with the signal 10 is another relay 19, hereinafter termed a stick relay. These different relays are each provided with armatures or contact fingers which are illustrated in the drawing conventionally. In practice, ordinarily each relay has only one armature, properly speaking, which in turn controls one or more contact fingers; but for simplicity the diiferent contact fingers or circuit controlling members of each relay will be termed armatures, and for convenience thesearmatures are given the same reference characters as the corresponding relay, with distinctive exponents added thereto. Although certain relays have been designated as track relays, certain others as line relays, and certain others as stick relays, these designations are chosen merely for the sake of convenience; and it should be clearly understood that there is in practice ordinarily no essential difference in construction and operation between the relays so designated, and further that each of these relays is of any one of the well known or ordinary types of relays used for signaling purposes.

Extending the full length of the track protected by the signaling system is an insulated conductor, commonly termed a common wire asd designated 33 in Fig. 2. As is well understood by those skilled in the art of railway signaling this common wire 33 forms a part of one or more controlling circuits extending between different signal 10- cations, and for convenience certain of the circuits hereinafter traced will be traced from the common wire 33 at one point back to this common wire at another point, it being obvious that the common wire serves to complete these circuits.

It should also be understood that while the controlling circuits for the signals 9 and 10 only are illustrated in Fig. 2, the controlling circuits for the signals 7 and 8 governing trafiic in the opposite direction are the same; and furthermore that the rela s and controlling circuits associated with t e signals 11 and 6 are the same as those shown in Fig. 2 associated with the signal 10, and that the relays and controlling circuits associated with the signals 5 and 12 may or may not be the same as those shown associated with the signal 10 in Fig. 2, as desired.

Each signal is controlled by a line relay; and the controlling circuit for the signal 9, which, as explained hereinbefore, is only that for controlling the signal 9 to two positions, may be traced as follows: commencing at the battery 20, conductor 21, armature 17 of the line relay 17 in its upper position, conductor 22, operating mechanism of the signal 9 (not shown), and conductor 23 back to the battery 20.

The controlling circuit for the signal 10 may be traced as follows: commencing at the battery 60, conductors 24, 25, 26 and 27, armature 18 of the line relay 18 in its upper position, conductor 28, armature 15 of the track relay 15 in its upper position,'conductor 29, operating mechanism of the signal 10, and conductors 30, 31 and 32 back to the battery 60.

The controlling circuit for the line relay 17 may be traced as follows: commencing at the common wire 33, conductor 34, line relay 17, conductor 35, armature 13 of the track relay 13 in its upper position, conductor 36, armature 14 of the track relay 14 in its upper position, conductors 37 and 38, armature 18 of the line relay 18 in its upper position, conductors 26, 25 and 24, battery 60, conductors 32, 31 and 39 back to the common wire 33.

There is a shunt for the armature 18 of the line relay 18 comprising conductors 38 and 40, armature 19 of the stick relay 19 in its upper position, and conductors 41, 25 and 26; and this shunt is closed when the stick relay 19 is energized. From a consideration of the circuit for the line relay 17 last traced and the shunt controlled by the stick relay 19, it is apparent that when the line relay 18 is deenergized and its armature 18 is in its lower position, the line relay 17 will also be denergized, unless the stick relay 19 is at that time energized.

The controlling circuit for the line relay 18 may be traced as follows: commencing at the common wire 33, conductor 42, line relay 18, conductors 43, 44, armature 15 of the track relay 15 in its upper position, conductors 45 and 46, armature 16 of the track relay 16 in its upper position, conductors 47 and thence through an armature controlled by the line relay (not shown) associated with the next signal to the right of the signal 10 governing traffic in the same direction, as for instance, the signal 11, this circuit for the line relay 18 being also controlled by the stick relay associated with said signal at the right.

The preliminarily energizing or pickup circuit for the stick relay 19 may be traced as follows: commencing at the battery 60,

conductors 24 and 25, armature 18 of the line relay 18 in its upper position, conductor 50, armature 15 of the track relay 15 in its lower position, conductors 51 and 52, stick relay 19 and conductors 53 and 32 back to the battery 60.

The maintaining or stick circuit for the stick relay 19 may be traced as follows: commencing at the battery 60, conductors 24 and 25, armature 18 of the line relay 18 in its lower position, conductor 54, armature 19 of the stick relay 19 in its upper position, conductors 55 and 52, stick relay 19, and conductors 53 and 32 back to the battery 60.

Operation: Assume that a train, traveling from right to left, in the direction indicated by the arrow Y, enters the stretch of single track shown in Fig. 1, while there is no other train present upon this stretch of track. lVhen this train enters the track section F it causes a deenergization of the line relay associated with the signal 11, which in turn deenergizes the line relay 18 associated with the signal 10, which in turn deenergizes the line relay 17 associated with the signal 9. WVhile the line relay for the signal 11 and its controlling circuit have not been illustrated in Fig. 2, the effect produced by the train entering upon the track section F upon the line relay associated with said signal 11 may be readily understood by considering that the track sections C and D shown in Fig. 2 are equivalent to the track sections E and F shown in Fig. 1, and that the line relay 18 is equivalent to the line relay associated with the signal 11, it being apparent from this that the shunting of the track relay connected to the track section F, by dropping its armature equivalent to the armature 16 breaks the circuit for normally energizing the line relay at the signal 11. The way in which the the circuit for normally energizing the line relay 17, since the stick relay 19 is not at this time energized by reason of the fact that the armature 15 of the track relay 15 is in its upper position and interrupts the pickup circuit for said stick relay. The de'elnergization of the line relays associated with the signals 11, 10 and 9 causes these signals to assume their biased position by interrupting their respective controlling circuits.

From the foregoing it can be seen that a train traveling from right to left, in the direction indicated by the arrow Y, will cause all of the opposing signals as 9, 10, and 11 to assume their stop position. As this train passes alongthe stretch of single track, the signals 6, 7 and 8 are permitted to assume an operated position successively to permit another trainto follow the first train, these signals being controlled in the manner to be presently described in connection with the signals 9 and 10, shown in Fig. 2

To enable a clear understanding of the way in which the signals may move to operated positions behind a train to permit following train movements, assume a train traveling from left to right, in the direction indicated by the arrow X. When this train enters the track section A it shunts the track relay 13, and the dropping of the armature 13 of this track relay interrupts the circuit normally energizing the line relay 17 thereby resulting in the dropping of the armature 17 of said line relay and the breaking of the controlling circuit for the signal 9, with the result that the signal 9 assumes its stop position. Also, the entranceof. a train into the track section A causes the signals 6, 7 and 8 to assume their biased or stop position, in the same way and for the reason hereinbefore pointed out in connection with the movement of the signals 9, 10 and 11 to their stop position when a train enters the stretch of single track from the right hand end; and, consequently, when the train under consideration enters the track section A, all opposing movements of trains are blocked.

Asthetrainunderconsiderationtravelingin the direction indicated by the arrow X proceeds and entersthe track section B, the sh unting of the track relay let and the dropping of the armature 14: of this relay opens another break in the controlling circuit for the line relay 17 thereby keeping this line relay deenergized and the signal 9 in its stop position, the signals 6, 7 and 8 being also held in the stop position. As the train progresses and enters the track section C, the track relay 15 is shunted and all of its armatures drop. The armature 15 of theline relay 15 breaks one ofthe two multiple paths, above described, over which current may now toenergize the line relay 18; but since the stick relay 19 is at the instantthe armature 15 drops deenergized and its armature 19 is inits lower position, current may flow along conductors 4:6, 19, through said armature 19 and along conductors 48 and 4,3 to the line relay 18. Consequently, although thetrack relay 15 is deenergized, the line relay 18 is not denergized immediately, and will remain energized until the stick relay 19 picks up its armature 19 The'signal 10, however, immediately assumes its stop position by reason of the fact that, its controlling circuit is broken by the dropping of the armature 15 of the track relayl5, so that,

regardless of the fact that the line relay 18 is still'energized, the signal 10 immediately assumes its stop position when the train first enters the track section G. The line relay 18 remains energized only for an instant after the train enters the track section I 0, however, since the dropping of the armature 15 closes the pickup circuit for the stick relay 19, the armature 18 of the line relay 18 being in its upper position; and as soon as the pickup circuit is established, all of the armatures of the stick relay 19 are raised, so that the armature 19 opens a break in the sole remaining parallel path over which current may flow to the line relay 18. Consequently, as soon as the stick relay 19 is energized, that is as soon as the armature 19 of said stick relay moves from its lowermost position, the line relay 18 is deenerglzed and its armature 18 commences to move toward its lower position. The armature 18 of the line relay 18 is preferably so constructed-that in dropping it will make contact with the conductor 54: before breaking contact with the conductor 50, this, arrangement being commonly termed a make -before-break contact. This makebefore-break contact may be obtained in various ways, but is illustrated in Fig. 2 conventionally as consisting of two resilient arms carried by the armature 18 which are so constructed that during the downward movement of the armature 18 the resiliency of the upper contact arm maintains electrical contact with the conductor 50 until the lower contact arm makes contact with the conductor 54:, but breaks contact with the conductor 50 as soon as the armature 18 reaches its lowermost position. By reason of this construction of the armature 18 ,.the stick circuit for the stick relay 19 is established before the pickup circuit is broken; and the stick relay 19, having been preliminarily energized, is maintained energized so long as the line relay 18 remains deenergized and its armature 18 is in its lower position.

\Vhen the stick relay 19 is energized its armature 19 closes the shunt for the armature 18 of the line relay 18, so that, although the line relay 18 is deenergized at this time, due to the presence of the train on the track section C, the line relay 17 may be reenergized as soon as this train passes entirely off from the track sections A and B. As the train progresses and enters the'track section D, the shunting of the track relay 16 and the dropping of its armature 16 opens another break in the controlling circuit for the line relay 18, thereby maintaining said line relay deenergized.

From the; foregoing it can be seen that when a train is traveling from left to right, in the direction indicated by the arrow X, the signal 9 may assume an operated position after this train has passed the signal 10; although the presence of a train on the track sections C and D would, if this train were moving from right to left. hold the signal 9.

in its biased or stop position. This change in the control of the signal 9 is caused by the energization of the stick relay 19, and serves to permit a following train to enter the stretch of single track at the left hand end, and other trains to follow that train, and so on, each following train in turn keeping the opposing absolute signal 8 in its stop position so as to prevent the entrance of any train into the stretch of single track at the right hand end.

Resuming the description of the operation when a train moves from left to right, in the direction indicated by the arrow X, and remembering that this train has been followed as far as the track section D, as the train passes from the track. section 'D into the track section E, the signal 11 is caused to assume its stop position; the stick relay (not shown) associated with this signal 11 is energized in the same way as hereinbefore described in connection with the energizationv of the stick relay 19; and after this stick relay at the signal 11 is energized, the armature of the line relay at this'signal drops. The dropping of the armature of the line .relay at the signal 11 does not, however, prevent the energization of the line relay 18 as soon as the train has entirely passed out of the track sections C and D, since thestick re lay at the signal 11 has been energized and,

as explained hereinbefore, establishes the shunt for the break made in the controlling circuit for the line relay 18 by the dropping of the armature of the line relay at the signal 11. Consequently, when the train entirely leaves the track sections C and D, the signal 10 may assume an operated position, which in practice would be the diagonalor caution position; and the signal 9 in turn may assume the vertical or clear position, so that another train traveling from left to right may enter the stretch of single track and follow the first train. The stick relay at the signal 11 which permits the signals 10 and 9 to assume an operated position, is maintained energized as long as the line relay at the signal 11 remains dee'nergized', which is as long as the train occupies the track sections E and F.

During this time while the train in question is occupying the track sections C and D, the signals 7 and 8 are held in their stop position, by reason of the fact, as explained hereinbefore, that the relay associated with signal 7 is deenergized and in turn causes the deenergization of the line relay at the signal 8. As the train progresses and occupies the track sections E andF, the absolute signal 8 is held in its stop position by reason of the deenergization. of the line relay at this signal 8, which line relay is controlled like the line relay 17 by the track relays connected to the track sections E and F. When the train has entirely left the track sections E and F, the line relay at the signal 8 may be energized, providing there is no other train in the stretch of single,

track following the first train; and 'also the line relay at the signal 11 will be reenergized, so that the signals 11 and 8 may assume an operated position, the stick relay at the signal 11 being de'e'nergized by the break of the stick circuit as the consequence of the reenergization of the line relay at the signal 11. In this way providing there is no other train in the stretch of single track which followed the first train, the signals are restored so as to permit a train to enter the stretch of single track at the right hand, end.

The significant features of this invention reside in the control of the stick relays, of which the stick relay 19 is given as an example; and in this connection it should be.

noted that these stick relays are energized by a train moving in one direction only. To illustrate, referring toFig. 2, a train moving from right to left will enter the track section D before it enters the track section, C, and \Vlll shunt the track relay 16 and deenergize the line raly 18, if said line relay is not already decnergized before shunting the track relay 15; and, consequently, the armature 18 of the line relay 18 opens a break in the pick up circuit for the stick relay before the shunting of the track relay 15 and the dropping of its armature 15 closes the normally open break in this pickup circuit. Obviously, until the pick up circuit of the stickrelay 19 is closed, and its armature 19 raised, the dropping of the armature 18 of the line relay 18cannot close the stick circuit for said stick relay. Nhen a train is traveling in the other direction, however, that is, in the direction indicated by the arrow X, in order that this train may properly pass the signal 10, the line relay 18 must be energized and the signal 10 in an operated position, so that, when the train enters the track section C, the shunting of the track relay 15 and the dropping of the armature 15 closes the pick up circuit for the stick relay 19, the deenergization of the line relay 18 and the dropping of its armature 18 being delayed, as hereinbetore explained, until the stick relay 19 has raised its armature 19 Ordinarily a relay, as they are constructed at the present time, will raise its armature quicker than it will cause its armature to drop and as a general proposition, the stick relay 19 will raise its armature to its uppermost po sition and establish the stick circuit before the armature of the line relay 18 drops and breaks the pickup circuit, even though the armature or contact linger 19 ot the stick relay l9 breaks contact with the conductor 19 as soon as the armature of said stick relay moves along slightly toward its upper position. It is preferably, however, to construct the armatures or contact fingers 19 and 19 of the stick relay 19 so that the contact fin ger 19 will make contact with the conductor 5-5 at the same time or very shortly after the contact finger 19 breaks contact with the conductor 19.

When the pickup circuit for the stick relay 19 is established, the stick circuit for said stick relay is established by the subsequent dropping of the armature 18 of the line relay 18; and due to make-before-break contact associated with said armature 18 it is assured that this stick circuit will be closed before the pickup circuit is broken. It should also be noted that each stick relay, as the stick relay 19, is not energized until it is necessary to use the controlling action which this relay is capable of performing; that is, the stick relay 19 is not energized'until a train enters the track section C, and it is not until this time that it is necessary to use the shunt around the armature 18 which is closed when said stick relay is energized. Furthermore, the proper energization of the stick relay 19 is not necessarily dependent upon the time required for it to raise its armature, or the time required for the track relay 15, or the line relay 18 to droy their armature; and if the stick relay 19 should for any reason, after it has been first installed, become slower in raising its armature, that will be, nevertheless no interference with the proper energization of this stick relay. Also, by reason of the arrangement of the controlling circuits for the stick relays, as shown in Fig. 2, it is possible to use the signaling system embodying this invention in connection with signals, such as the well known light signals, which do not have any operating parts, because it is not necessary in the arrangement of the controlling circuits for the stick relays shown and described, to have a circuit controller which is operated by the mechanism operating a semaphore arm in order to properly energize these stick relays. It may happen that the stick relay, as relay 19, will forsome reason fail to raise its armature when current is'applied to its coils, or there may be a break in some part of the pickup circuit for this relay; but, in either case, the failure of the stick relay to raise its armature will not produce any dangerous condition by improperly operating the signals, since the signal 9 will indicate stop as long as the track sections 'A' and B are occupied, regardless of the condition of the line relay l8 and the stick relay 19, and the armature 15 of the track relay 15 will cause the signal 10 to assume its stop position whenever a train occupies the track section C, regardless of the condition of the line relay 18 and the stick relay 19.

Although I have particularly described the construction of one physical embodiment of my invention, and explained the operation and principle thereof, neverthe less, I desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodiment 01 the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1 In a signaling system for railroads, in combination: two track circuit sections; a circuit controller governed by one track circuit section and closed when that track circuit section is occupied; a second circuit controller governed by both of said track circuit sections and opened when either of said track circuit sections is occupied; a de 115 vice adapted to be governed electrically; a circuit for energizing said device including in series said circuit controllers; means governed by said device for preventing the opening of said second circuit controller by 120 a train on said first mentioned track circuit section until said electrically operable dev ce has operated; and means for signaling con.- trolled by said device.

2. In a signaling system for railroads, in 125 combination: two. track circuit sections; .a

.circuit controller governed. by one track track circuits and open when either is occupied; a stick relay having an armature; a pickup circuit for said stick relay including said circuit controllers in series; means governed by said stick relay for preventing the opening of said second circuit controller by a train on said first mentioned track circuit section until said stick relay has raised its armature; means for maintaining said stick relay energized controlled by its armature and by both of said tlitCi circuit sections; and means for signaling governed by said stick relay.

3. In a signaling'system for railroads, in combination: twotrack circuit sections each having a track relay; a relay; a controlling circuit for said relay including cooperating contacts operated by the track relay of each of said track sections and open when either of said track relays is shunted; a circuit controller governed by said relay and closed when said relay is energized; a second circuit controller governed by the track relay of one of said track sections and closed when that track relay is shunted; a stick relay; a pickup circuit for said stick rela including in series said circuit control ers; a shunt for the cooperating contacts of the track relay of said first mentioned track circuit which is governed by said stick relay and is closed when said stick relay is deenergized; a stick circuit for said stick relay which is governed by the relay itself and by the track relays of both of said track sections; and means for signal ing controlled by said stick relay.

4. In a signaling system for railroads, in combination: a stretch of track divided into track circuit sections; a first signal and a second signal for governing trafiic over said stretch. in the same direction; a controlling circuit for the first signal; means for interrupting said circuit when a predetermined portion of the stretch of track in advance of the second signal is occupied; electrically operable means which when energized nullifies the controlling efi'ect produced on said circuit by the presence of a train on said portion of the stretch of track; a preliminary energizing circuit for said electrically operable means; a circuit con troller included in said preliminary energizing circuit and governed by the track circuit sections of said portion of the stretch of track, said circuit controller being open when anyone of said track circuit sections is occupied; a second circuit controller included in said preliminary energizing circuit and governed by the track circuit section next in advance of said signal, said second circuit controller being closed when that track circuit section is occupied; means governed by said electrically operable means for preventing the opening of said first circuit controller by a train on said track circuit section next in advance of the second signal until said electrically operable means has operated; and means for maintaining said electrically operable means in its operated condition after it has initially operated so long as said portion'of track in advance ofthe said signal is occupied.

5. In a signaling system for railroads, in combination: a stretch of track divided into track circuit sections; a first signal and a second signal for governing trafiic in the same direction over said stretch; a control relay for each signal; a controlling circuit foreach control relay governed by the track circuit sections protected by the corresponding signal; a circuit controller governed by the control relay of the second signal and closed only when that control relay is energized; a second circuit controller governed by a track circuit section next in advance of the second signal; a device adapted to be governed electrically; a preliminary energizing circuit for said device including in series said circuit controllers; means governed by said device for preventing the deenergization of the control relay of the second signal and the opening of said first circuit controller by a train on said track circuit section next in advance of the second signal until said device has operated; means for maintaining said device in its operated condition after it has been initially operated so long as the control relay of the second signal is deenergized; a third circuit controller governed by the control relay of the second signal and included in the controlling circuit for the control relay of the first signal, said third circuit controller being open when said control relay of the second signal is deenergized; and a normally open shunt for said third circuit controller governed by said device and closed when said device is operated.

6. In a signaling system for railroads, in combination: two track circuit sections; a circuit controller governed by one track circuit section and closed when that track circuit section is occupied; a second circuit controller governed by both track circuit sections and open when either is occupied; a 115 stick relay having an armature; a pickup c1rcu1t fOZQSiLlCl stick relay including 1n series sald c1rcu1t controllers; means governed by said stick relay for preventing the opening 7 of said second circuit controller by a train on said first mentioned track circuit section until said stick relay has raised its armature; circuit controlling means governed by both of said track circuit sections and closed when either of said track circuit sections is occupied, said circuit controlling means being subjected to the same controlling influence as said second circuit controller and being closed before said second circuit con troller is opened by a train on either of said track circuit sections; a stick circuit for said stick relay governed by said circuit controlling means and by the armature of the relay itself; and means for signaling controlled by said stick relay. I

7. In a signaling system for railroads, in combination: two track circuit sections; a circuit controller governed by one of said track circuit sections and closed when that track circuit section is occupied; a relay; a controlling circuit for said relay controlled by both of said track circuit sections and interrupted when either of said sections is occupied; cooperating contacts operated by said relay; one set of said contacts being a stick relay; means controlled by the stick relay for governing said first mentioned relay; a pickup circuit for'said stick relay including in series said circuit controller and said first mentioned set of contacts; a stick circuit for said stick relay including said second mentioned set of contacts; and means for signaling controlled by said stick relay.

NEIL D. PRESTON. 

